1. Field of the Invention
This invention relates to a frequency correction system for correcting a frequency characteristic of a network, and more particularly to a frequency correction system for correcting a frequency characteristic of an optical network which repeats and transmits an analog signal.
2. Description of the Related Art
Conventionally, an optical network connected in an analog repeating connection is composed of optical repeaters connected in multiple stages. However, where optical repeaters are connected in multiple stages, displacements in frequency characteristic are accumulated and this deteriorate the frequency characteristic of the network. Therefore, in order to flatten the frequency characteristic of the network, the frequency characteristic of each of the optical repeaters connected in multiple stages is defined strictly and adjusted.
Further, if the frequency characteristic of the network is bad after the optical repeaters are connected in multiple stages, then the frequency characteristic is adjusted again to effect correction of the frequency characteristic of the network.
However, such a conventional optical network as described above is disadvantageous in that, since, in order to flatten the frequency characteristic of the network, the frequency characteristics of the optical repeaters connected in multiple stages must be defined strictly and adjusted, and, when the frequency characteristic of the network is bad after the optical repeaters are connected in multiple stages, the frequency characteristics must be adjusted again, requiring man-hours for the adjustment.
The conventional optical network is disadvantageous also in that, when it is tried to increase optical repeaters to change the system after the network is constructed, since there is the possibility that the frequency characteristic of the network may be deteriorated, the frequency characteristic must be adjusted again.